Cardboard 101 - Inventionland Education

Cardboard 101

Why Cardboard

Cardboard modeling is a staple skill of professional industrial designers and amateur model makers alike. Why wouldn't it be? Cardboard is inexpensive, easy to work with, abundant, and has an excellent strength per weight ratio. At Inventionland, all of our three-dimensional design projects are realized in cardboard long before the first prototype is built or the first computer model is rendered.

Kinds of Cardboard

The first key to effectively modeling with cardboard is understanding that not all cardboard is created equal. Each different kind has its own advantages and disadvantages.

Cardstock and Poster Board Cardstock is essentially thick paper. To make a comparison, a sheet of typical printer paper is rated as 20 pound paper. In this case pounds refers to the thickness. The "heavier" the paper, the thicker it is. Click here for an article that is ridiculously complex on the subject. Card stock, like the kind used for business cards, is typically rated at 90 to 110 pounds. It is available at most office supply stores and most desktop computer printers have the capability of printing on card stock. Poster board is thicker than cardstock, but is easier to find in large sheets. Oftentimes dollar stores will carry poster board as cheap as fifty cents per sheet. They will sometimes have different colors available as well. Poster board and cardstock are also easily cut with safety scissors. While both cardstock and poster board have these advantages, neither are as thick, cheap, or readily available as cardboard.

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Cardboard 101

Chipboard Chipboard is thicker and stronger than poster board. It is the material used to make notebook covers, cereal boxes, case boxes for cans of soda and boxes for the bulk of small-to-medium sized consumer products. It's also used to make the cardboard tubes at the center of rolls of toilet paper, paper towels, and gift wrap. Note: Paper towel and toilet paper tubes can be very useful for building cardboard models. Make sure to keep a few in your cardboard supply!

Because chipboard is used to box so many products, obtaining it is as simple as not throwing away some boxes! (How's that for cheap?) Also, chipboard can be cut with scissors although it is a bit more difficult.

Corrugated Cardboard When most people imagine cardboard, corrugated cardboard is what they think of. Typical corrugated cardboard is nothing more than a sheet of paper with a pattern of tiny waves (called corrugations) sandwiched between two other sheets of paper that have been glued to each side. The most common use for corrugated cardboard is to make case boxes used for shipping products. It has excellent compression strength when force is applied on the axis of the corrugations. It also has very good bridging strength as long as both ends of the corrugations bearing the load are supported.

Figure 1: The corrugations shown here run vertically. They can support a LOT of weight!

Figure 2: The corrugations shown here run from brick to brick. In this way, they have excellent bridging strength.

Figure 3: The corrugations here run from from front to back. In this way, they collapse

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Cardboard 101

VIDEO CONTENT: Click HERE to see a short video that demonstrates the strength and weakness of corrugated cardboard.

Corrugated cardboard readily collapses along the corrugations when force is applied in a way where one or both ends of the corrugations are not supported. That means that it bends easily in one direction but is extremely resistant to bending in the other.

Corrugated cardboard comes in a range of thicknesses referred to as "flutes." See the chart below for standard flute thicknesses:

Flute A flute B flute C flute D flute F flute

Thickness in inches 3/16" 1/8" 5/32" 1/16" 1/32"

Thickness in mm 4.80 3.20 4.00 1.60 0.80

Working with Cardboard

Cutting While cutting cardstock, poster board, and most chipboard can be done easily and safely with scissors, corrugated cardboard can be much more difficult. Even when you succeed while using scissors, the edges often look torn and uneven.

There are other tools available that are for cutting corrugated cardboard. This section will discuss the different options available as well as their advantages and disadvantages.

WARNING: The following section talks about a variety of cutting tools. ANY time children have access to cutting tools of ANY kind, they should be supervised by an adult. Many of the tools listed are DANGEROUS. Use discretion when deciding what is the best and safest option for your students.

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Safety Scissors As mentioned above using safety scissors can be difficult and the results are rarely attractive. The advantage, however, is that just about everyone has access to scissors. Most households have several pairs in one place or another. Scissors are also cheap; most dollar stores have scissors for sale for a dollar. Lastly, scissors are relatively safe. Most children can safely use scissors SUPERVISED within first grade.

Cardboard Scissors Sometimes called "corrugated cardboard scissors" or "cardboard cutting scissors," these heavy duty scissors feature thick, angled blades that easily cut through corrugated cardboard as well as many other craft materials. They often have large, ergonomic handles that give the user plenty of leverage and control as they cut. These scissors are relatively safe to use, although supervision is ALWAYS recommended, especially for young children. (See the warning above.)

The disadvantage with cardboard scissors is that they can be harder to find in stores. You won't find these at most general retailers. You MAY find them at craft, hobby, or art supply stores. They are also readily available from online retailers such as Amazon. The other disadvantage is that these items are not cheap. Online prices range from $18 to well over $20 per pair. Retail locations will likely charge up to $30.

Serrated Cardboard Cutters These cutters at first glance look like a knife, but upon closer inspection reveal that the "blades" are lined with tiny serrations. These tools ARE NOT SHARP. The blades feel dull to the touch, making them a very safe option, especially for younger students. (See the warning above.)

While it would be difficult to cut skin with these cutters, they are tremendously effective when used on cardboard. Simply use a back and forth motion while cutting and let the blades do the work. Smooth controlled cuts are made safely and easily using these cutters.

Much like cardboard scissors, there are two significant drawbacks with serrated cardboard cutters. The first is that they are more difficult to find at retail locations. Again, a person MAY be able to find them at craft, hobby, or art supply stores, but it is unlikely they could be found elsewhere. The second drawback, again, is price. A single cutter can cost around $10. Price breaks can reduce the per unit cost, but the customer must buy more at one time to get the savings.

At the time of this writing, we could only find one company making this product. A company called "Canary" sells their "Canary Cardboard Cutters" on Amazon. There are a variety of different styles, but they all feature the "safe" serrated blade.

Hobby Knives and Utility Blades Hobby knives and utility blades are by far the MOST DANGEROUS OPTION for cutting cardboard. In the history of Inventionland, the tool that has been involved in the MOST accidents requiring a person to go to the hospital has been the hobby knife. These blades are insanely sharp and easy to lose control of. We do NOT recommend these tools for students.

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Cardboard 101

That being said, if a teacher or other responsible adult chooses to use tools like these, there are advantages to them. First of all, both (when sharp) are extremely effective at cutting cardboard. The cut edges of the cardboard will be crisp and clean. Hobby knives are the tool of choice for most industrial designers and hobbyists because of the highly detailed and precise cutting that can be done with them. Also, they are easy to come by. Both hobby knives and utility blades can be found at office supply stores, hardware stores, home centers, and sometimes general retailers. They can also be found at most craft, hobby, and art supply stores. Of course, they are also available from online retailers as well. Replacement blades are as easy to find as the tools, usually being sold by the same retailers. These tools are also relatively cheap. While there are always more expensive name brands, non-name brands can cost only a few dollars for the tool, which will usually come with a small number of replacement blades.

Aside from the aforementioned danger, another drawback of hobby knives and utility blades is that the blades dull quickly as they are used. For best results, blades should be changed often which is sometimes inconvenient, and can start getting costly during large projects. Additionally, dull blades lead to accidents. A person will instinctively use more force as their blade gets less effective. When that happens the blade can easily slip or break, causing the user to cut themselves, or someone else by accident.

VIDEO CONTENT: Click HERE to see a short video about different cardboard cutting tools.

Making Cardboard Bend to Your Will

It seems counter-intuitive that bending a material made of paper would be challenging, yet anyone who has spent time working with the material can tell you that it rarely folds in predictable or desirable ways without using a few tricks.

Scoring: Have you ever tried to fold a piece of cardboard, but instead of a nice straight line, like you get when folding paper, the fold looks uneven and irregular? Cardboard of all thicknesses tends to fold in irregular ways unless you score the cardboard before you attempt to fold it.

Scoring is the act of weakening a piece of material along a line where you intend to fold the material. This is done by drawing a line where you plan to make the fold, then tracing that line using a ruler and some kind of rigid stylus to press into the material and create a crease for the fold to follow. The stylus can be any rigid implement that comes to a dull point. Here are some things you can try: A clicker pen with the tip retracted. A pen with the cap on if the cap has a pointed top. A stick or dowel rod sharpened to a dull point (like with a pencil sharpener). A ball point pen that has dried up. The tip of a pair of scissors with the blades closed.

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